Port ReviewRound to use Eloquent model

[taslangraham]

Description:
The ReviewRound class and ReviewRondDAO are implemented using the old-style DAO pattern. Migrate to Eloquent model.

Steps to test the changes:
These steps can include user interactions, database queries and API requests

1. Using the site '...'
2. Click on '....'
3. Using a DB query '...'
4. This table should have '...'
5. POST Request '...'
6. Should return '...'

Solution: What the proposed solutions are and additional affected areas
Upgrade existing ReviewRound data model to use Eloquent.

What application are you using?
OJS, OMP or OPS version X.X.X-X

Additional information
See comment #12207 (comment)

Draft Pull Requests
pkp-lib: #12277
ojs: pkp/ojs#5307
omp: pkp/omp#2220
ops: pkp/ops#1197